JPH1020236A - Illumination optical system and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly illuminate an object by setting a distance between secondary light sources so that the distance in a 1st direction where the coherence of luminous flux made incident on an optical integrator is high may be longer than that in a 2nd direction where the coherence is low. SOLUTION: The luminous flux having the anisotropy of the coherence and emitted from the light source 1 such as an excimer laser is deformed to have the desired shape of the luminous flux by a beam shaping optical system 2, and made incident on a fly-eye lens 3 and a condenser lens 4 being the optical integrator. The luminous flux passing through the lens 4 is made to have the desired shape of illuminating area by a diaphragm 5 and projected to a base plate 9 coated with photosensitive material through an optical system 6, a mask 7 and a projection optical system 8. In such a case, the element lenses which constitute the lens 3 form a rectangular aperture whose side parallel with the direction where the coherence of the incident luminous flux is high is made longer than the side in the direction where the coherence is low and orthogonal to the former side. Thus, the spatial coherency in the direction where the coherence is high is made low and the mask 7 is uniformly illuminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an illumination optical system,
In particular, the present invention relates to an illumination optical system suitably used for an exposure apparatus for manufacturing semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, and devices such as magnetic heads.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor element is manufactured by using photolithography technology, a transfer pattern of a photomask (mask) is coated with a photoresist or the like via a projection optical system, or a substrate such as a glass plate. 2. Description of the Related Art A projection exposure apparatus that performs exposure transfer on a substrate (hereinafter simply referred to as a substrate) is used. In recent years, there has been a demand for improvement in the resolution of a projection optical system in accordance with high integration and miniaturization of semiconductor elements.

In order to respond to this high resolution, a pulse laser such as an excimer laser has been used in a projection exposure apparatus as a light source in the far ultraviolet region.

On the other hand, when a mask is illuminated with a light beam from a coherent light source such as an excimer laser, there arises a problem that unevenness of illuminance distribution due to interference fringes occurs and adversely affects exposure accuracy. In order to avoid this, conventionally, the position of the light beam entering the optical integrator such as a fly-eye lens is shifted and the exposure is performed with multiple pulses while changing the phase of the interference fringes. The exposure accuracy was not affected.

[0005]

However, in the above-described method, a member for shifting the incident position of the light beam is driven, for example, when the incident position of the light beam incident on the optical integrator is shifted by a vibrating mirror. Means were required, and the configuration was complicated.

An object of the present invention is to solve the above-mentioned problems and to provide an illumination optical system capable of uniformly illuminating an object.

[0007]

In order to achieve the above object, an illumination optical system according to a first aspect of the present invention has an optical integrator on which a light beam having coherence anisotropy is incident, and is formed by the optical integrator. An illumination optical system for illuminating an object with a light beam from a secondary light source, wherein an interval between the respective secondary light sources is a first direction in which a coherence of a light beam incident on the optical integrator is higher in a first direction. It is characterized in that it is larger than the interval in the second direction having a lower coherence than the direction.

The illumination optical system according to the second aspect of the present invention has an optical integrator on which a light beam having coherence anisotropy enters, and an illumination optical system for illuminating an object with a light beam from a secondary light source formed by the optical integrator. The optical integrator has a plurality of element lenses, and the aperture of the element lens has a dimension in the first direction where the coherence of the light beam incident on the optical integrator is higher than that in the first direction. And is larger than the dimension in the second direction having low coherence.

By applying the illumination optical system of the first and second aspects of the present invention to an exposure apparatus, semiconductor devices such as ICs and LSIs, imaging devices such as CCDs, and devices such as magnetic heads can be manufactured accurately. .

[0010]

FIG. 1 is a schematic view of a main part of a projection exposure apparatus having an illumination optical system according to the present invention.

A light beam having anisotropy of coherence emitted from a light source 1 such as an excimer laser is transmitted to a beam shaping optical system 2.
Then, the light beam is transformed into a desired light beam shape, and enters a fly-eye lens 3 and a condenser lens 4 which are optical integrators. The light beam that has passed through the condenser lens 4 has a desired illumination area shape by the stop 5, and irradiates the substrate 9 coated with a photosensitive material via the optical system 6, the mask 7, and the projection optical system 8. Thus, the pattern formed on the mask 7 is exposed and transferred to the substrate 9. The stop 5, the mask 7, and the substrate 9 are arranged at optically conjugate positions.

FIG. 2 shows the fly-eye lens 3 as viewed from the light source 1 side.

As shown in FIG. 2, the element lens constituting the fly-eye lens 3 has a rectangular opening in which the side parallel to the direction of high coherence of the incident light beam is longer than the side perpendicular to the direction of low coherence. doing. The lengths of these sides are determined by the coherence of the luminous flux, and are determined to have the most uniform illuminance distribution obtained by simulation, actual measurement, or the like.

FIGS. 3 and 4 show detailed views from the beam shaping optical system 2 to the mask 7 in this embodiment. FIG. 3 is a cross-sectional view of a plane parallel to the direction of high coherence of the incident light beam, and FIG. 4 is a cross-sectional view of a plane parallel to the low coherence direction.

As described above, the dimensional ratio of the apertures of the element lenses of the fly-eye lens 3 differs depending on the direction in which the coherence is high and the direction in which the coherence is low. Therefore, as shown in FIGS. Depends on the direction of high and low coherence. Therefore, the mask 7 can be illuminated with an illumination area of a predetermined shape defined by the aperture 5 although the illumination area of the light beam that reaches the surface of the aperture 5 via the condenser lens 4 is different.

Another example of a fly-eye lens is shown in FIG. As in this example, the aperture of the element lens may have an elliptical shape having a major axis in the direction of higher coherence of the incident light beam and a minor axis in the direction of lower coherence. 2 and 5, the effects of the present invention can be expected as long as the opening shape has a longer coherence direction than a low coherence direction.

As described above, according to the present invention, by increasing the opening size of the fly-eye lens in the direction of high coherence as compared with the direction of low coherence, the spatial coherency in the direction of high coherence is reduced and the mask 7 is made uniform. Can be illuminated.

FIG. 6 is a view showing another embodiment of the present invention, and is a schematic view of a main part of a scanning type exposure apparatus.

The difference from the previous embodiment is that a mask scanning unit 10 and a substrate scanning unit 11 for synchronously scanning a mask and a substrate are provided. The entrance opening of the element lens of the fly-eye lens 3 is arranged conjugate with the mask 7.

FIGS. 7 and 8 show detailed views from the beam shaping optical system 2 to the mask 7 in this embodiment. FIG. 7 is a cross-sectional view of a plane parallel to the direction of higher coherence of the incident light beam, and FIG. 8 is a cross-sectional view of a plane parallel to the lower direction of coherence.

In the present embodiment, since the entrance opening of the element lens constituting the fly-eye lens 3 is conjugate with the mask 7, and thus conjugate with the stop 5, the luminous flux projected on the surface of the stop 5 Has a shape similar to the shape of the entrance opening of the element lens.

In general, in a scanning type exposure apparatus, a rectangular illumination area whose scanning direction is shorter than the non-scanning direction is formed, and the mask 7 and the substrate 9 are synchronously scanned to expose an exposure area wider than the illumination area. Do. Also in this embodiment, various shapes can be adopted for the aperture of the element lens as in the previous embodiment. However, when the aperture shape of the element lens is rectangular as shown in FIG. Since the shape of the light beam on the surface is a rectangle similar to the aperture of the element lens as described above, if the short side direction is configured to be the scanning direction of the mask 7 and the substrate 9, an illumination area is formed by the stop 5. Therefore, the amount of light to be shielded is small and the light utilization efficiency is high.

Next, a method of manufacturing a semiconductor device using the exposure apparatus of the present invention will be described.

FIG. 9 shows a flow of manufacturing semiconductor devices (semiconductor chips such as ICs and LSIs, liquid crystal panels and CCDs).
In step 1 (circuit design), the circuit of the semiconductor element is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer (substrate 9) is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a preprocess, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming chips using the wafer created in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor element created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 10 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer (substrate 9)
Oxidizes the surface of the Step 12 (CVD) forms an insulating film on the surface of the wafer. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), a resist (sensitive material) is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose a wafer using the circuit pattern image of the mask (mask 7). Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist are removed. Step 1
In step 9 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

By using such a manufacturing method, it becomes possible to manufacture a highly integrated semiconductor device which has been difficult in the past.

[0027]

As described above, according to the present invention,
The object can be illuminated uniformly.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a projection exposure apparatus having an illumination optical system according to the present invention.

FIG. 2 is a view of a fly-eye lens as viewed from a light source side.

3 is a detailed sectional view of a plane parallel to a direction in which coherence is high from a beam shaping optical system to a mask in the projection exposure apparatus of FIG.

4 is a detailed sectional view of a plane parallel to a direction in which coherence is low from a beam shaping optical system to a mask in the projection exposure apparatus of FIG.

FIG. 5 is a diagram of another example of a fly-eye lens viewed from a light source side.

FIG. 6 is a schematic view of a main part of a scanning exposure apparatus having an illumination optical system according to the present invention.

FIG. 7 is a detailed sectional view of a plane parallel to a direction in which coherence is high from a beam shaping optical system to a mask in the scanning exposure apparatus of FIG. 6;

8 is a detailed sectional view of a plane parallel to a low coherence direction from the beam shaping optical system to the mask in the scanning exposure apparatus of FIG.

FIG. 9 is a view showing a manufacturing process of the semiconductor element.

FIG. 10 is a diagram showing details of a wafer process during the step of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Beam shaping optical system 3 Fly-eye lens 4 Condenser lens 5 Aperture 6 Optical system 7 Mask 8 Projection optical system 9 Substrate 10 Mask scanning means 11 Substrate scanning means

Claims (9)

[Claims] 1. An illumination device comprising: an optical integrator on which a light beam having coherence anisotropy is incident; a plurality of secondary light sources formed by the optical integrator; and an object for illuminating an object with light beams from the plurality of secondary light sources. In the optical system, the interval between the secondary light sources is such that the interval of the light beam incident on the optical integrator in the first direction where the coherence is high is lower in the second direction where the coherence is lower than the first direction. An illumination optical system characterized in that the distance is larger than the distance of the illumination optical system. 2. A light source for supplying light having anisotropy of coherence, and an optical integrator on which a light beam supplied by the light source is incident, wherein a plurality of secondary light sources formed by the optical integrator are provided. In an exposure apparatus that illuminates a mask using a light beam and exposes and transfers a pattern of the mask onto a substrate, an interval between each of the secondary light sources is set to a distance in a first direction in which a light beam incident on the optical integrator has a high coherence. The exposure apparatus is characterized in that the distance is larger than the distance in the second direction, which has lower coherence than the first direction. 3. The exposure apparatus according to claim 2, further comprising: means for scanning the mask and the substrate while synchronizing the same, wherein a scanning direction of the mask and the substrate is equal to the second direction. 4. An exposure apparatus according to claim 2, wherein said light source is an excimer laser. 5. An illumination for providing an optical integrator on which a light beam having coherence anisotropy is incident, forming a plurality of secondary light sources by the optical integrator, and illuminating an object with light beams from the plurality of secondary light sources. In the optical system, the optical integrator has a plurality of element lenses, and an opening of the element lens has a dimension in a first direction in which a coherence of a light beam incident on the optical integrator is higher in the first direction. An illumination optical system, wherein the dimension is larger than a dimension in a second direction having a lower coherence. 6. A light source for supplying light having anisotropy of coherence, and an optical integrator on which a light beam supplied by the light source is incident, wherein a plurality of secondary light sources formed by the optical integrator are provided. In an exposure apparatus that illuminates a mask using a light beam and exposes and transfers a pattern of the mask onto a substrate, the optical integrator has a plurality of element lenses, and an opening of the element lens is provided for a light beam incident on the optical integrator. An exposure apparatus, wherein a dimension in a first direction having a high coherence is larger than a dimension in a second direction having a low coherence as compared with the first direction. 7. The exposure apparatus according to claim 6, further comprising: means for scanning while synchronizing the mask and the substrate, wherein a scanning direction of the mask and the substrate is equal to the second direction. 8. An exposure apparatus according to claim 6, wherein said light source is an excimer laser. 9. A device manufacturing method, comprising manufacturing a device using the exposure apparatus according to claim 2. Description: